Experimental observation of quantum reflection far from threshold

Phys Rev Lett. 2003 Nov 7;91(19):193202. doi: 10.1103/PhysRevLett.91.193202. Epub 2003 Nov 6.


We present first experimental evidence for quantum reflection, originating exclusively from an attractive potential between an atom and a solid surface, at energies far from the threshold E(i)-->0. The system of light and stable 3He atoms scattering from an alpha-quartz crystal allows confirmation of recent theory on quantum reflection up to its asymptotic behavior, determined by the nonretarded van der Waals potential -C(3)/r(3). From the data, the gas-solid interaction potential is deduced quantitatively, covering the energy region, in which retardation plays a role.